Add boot session stable sampling to AppFeaturesOps puller.

Refactoring of existing pullers.
Random seed added which should be stable for single boot session
Sampling rate is approximated to adjust for number of
packages and features used on individual device over last day.

Bug: 143519689

Test: make statsd_testdrive && ./out/host/linux-x86/bin/statsd_testdrive 10075
Test: make statsd_testdrive && ./out/host/linux-x86/bin/statsd_testdrive 10060
Change-Id: I43c940636f9eeb22fa7cd74c2ec5848ed641ee0f